Vol. 52.] NICKEL- BEARING SERPENTINE. 453 



small angles up to about 10 . 1 The mineral (if it is a single 

 one) in some respects resembles antigorite, but that is defined as 

 slightly green in colour, with one very well-marked cleavage, 

 a slight dichroism and straight extinction.' 2 That this is one 

 of the group of minute minerals included under the name 

 serpentine cannot, we think, be doubted, and one of us has 

 frequently met with both the above-mentioned varieties in 

 Alpine serpentinous rocks which have been subjected to great 

 mechanical disturbance. 



(b) A clear colourless mineral in granules, grains, and rather rude 



prismatic shapes, sometimes occurring in groups as if they 

 were remnants of larger crystals ; where these are of sufficient 

 size and regularity for measurement, the mineral proves to be 

 an augite and some of the grains retain traces of a cleavage, 

 indicative of diallage. 



(c) Here and there we find grains with an orange-yellow tint, 



which, however, we believe, are only the same mineral stained, 

 probably with an iron oxide. 



(d) Opaque black granules or grains, without definite shape, often 



more or less clustered. Examination with reflected light 

 shows most of them to be an iron oxide, generally magnetite, 

 but it indicates the occasional presence of a mineral, somewhat 

 intermediate in colour between pyrite and native copper. One 

 of us possesses, — owing to the kindness of Prof. Ulrich— 

 a small quantity of the awaruite found in river-sands on 

 the west coast of the South Island, New Zealand, and de- 

 scribed by him 3 ; and after a careful study of the two he 

 ventures to pronounce this also to be awaruite. 



The mode in which the above minerals are associated and the 

 structure exhibited in the slices indicate beyond question that the 

 rock has been greatly crushed, somewhat sheared, and occasionally 

 much crumpled. Their relations one to another make it highly 

 probable that some of the serpentinous mineral (antigorite ?) has 

 replaced augite, 4 but in other cases this constituent suggests an 

 independent origin, and in one it occurs in association with the 

 iron oxide, as in an ophitic structure. The reconsolidation of the 

 rock since the epoch when the crushing took place seems to have 

 been practically complete, the only macroscopic effect being a very 

 slight schistosity. This, however, does not hold good in every part 



1 I find these chiefly among the larger, brighter-coloured flakes. It is 

 possible that a small flaky hornblende may occur in the rock, but I cannot 

 ascertain more than that some flakes extinguish at small angles. — T. Gr. B. 



2 Teall, 'British Petrography,' 1888, p. 113. 



8 Quart. Journ. Geol. Soc. vol. xlvi. (1890) p. 619. This mineral has also 

 been described from Scandinavia and Saxony. 



4 My work among Alpine serpentines leads me to the conclusion (which I 

 hope before long to set forth more fully) that the so-called 'antigorite' is more 

 indicative of the action of severe pressure than of the former presence of 

 augite.— T. G. B. 



